Reciprocating tool actuating device



Nov.v 18, 1952 A, A- HUTCHlNs 2,618,242

RECIPROCATING TOOL ACTUATING DEVICE Filed Feb. 2l. 1949A l' i i l i IN VEN TOR. L MA Afa TCH/Ns,

Patented Nov. 18, 1952 UNITED STATES PATENT OFFICEl RECIPROCATING TOOL ACTUATING DEVICE Alma A. Hutchins, Pasadena, Calif.

Application February 21, 1949, Serial No. 77,461

7 claims. 1

This invention relates generally to improved tool actuating devices, and concerns more particularly novel pneumatically powered units for reciprocating sanders, files, saws, and the like.

As is well known, the work engaging portion of a reciprocating tool is generally susceptible to rather rapid wear unless operated at a fairly high speed. Consequently, a major object of the invention is to provide a tool actuating device operable at a relatively high reciprocating speed for assuring maximum useful life of the carried tool. This result is effected by the employment of a fluid pressure operated mechanism designed to be power driven in reverse directions and especially adapted for rapid reversal of motion at either end of its travel. Specifically, I provide a new type of pneumatic control Valve operable to quickly and automatically alter the course of fluid flow in accordance with reciprocating moiton of a pair of power pistons. Preferably, the valve means are carried by and between a pair of opposed pistons to which pressure fluid is alternately admitted.

A further object of the invention is to provide a reciprocating tool actuating device of such simplicity as to minimize the possibility of mechanical failure and to permit the use of power driven sanders and the like where the cost of such tools has previously prevented their use. In accordance with the invention, I employ a single moving unit comprising Valve and piston means movable together and directly carrying a tool holder.

The above and further features and objects of the present invention will be better understood from the following detailed description of the typical embodiment illustrated in the accompanying drawing, in which:

Fig. 1 is a perspective view of a tool actuating `device with a sanding block attached;

-3-.3 of Fig. 2;

- Fig. 4 is a longitudinal section taken on line 4-4 of Fig. 3; and

Fig. 5 is a side elevation of the slide valve.

The illustrated tool reciprocating device comprises essentially a body section generally indicated at IIJ, a piston and valve assembly adapted for bodily reciprocation within section I0, tool holder I2 carried by and movable with the piston and valve assembly, and nger operated control valve I3. Though, of course, any convenient type 0f reciprocating tool may be carried by tool holder I2, the device is typically illustrated as carrying a sanding block 58, secured to the holder by screws I4 and presenting on its work engaging surface sand paper I5.

Body section I0 includes a cylinder IB, at one side of which is carried elongated handle Il having vtransverse flanges at itsy ends disposed across and closing opposite ends of the cylinder. Cylindrical insert or valve block I8, of an external diameter corresponding to the internal diameter of cylinder I6, is located centrally within the cylinder, as seen in handle and cylinder I6, and into insert I8 to rigidly retain these three members in the illustrated relation.

As seen in Fig. 4, insert |`8 contains an axially extending central bore 20, within which the slide valve is receivable, as will later appear. The insert also contains a radially extending inlet passage 2| communicating with inlet line 22 through L connection 59 and control Valve I3. Extending radially in a direction opposite passage 2|, the insert contains a pair of axially spaced fluid discharge passages or slots 23 and 24, registering with escape slots 25 and 26 of the cylinder.

Valve I3 is of known type having a plunger 21 axially movable in barrel 28 and normally urged by coil spring 29 to the closing positions shown in' Fig. 4. As will be understood, plunger 21 maybe actuated axially to the right, as seen in Fig. 4, by finger pressure exerted against button 30, vto permit passage of compressed air or other pressure fluid about annular groove 3| of the plunger and into inlet passage 2| of the valve insert.

Assembly I I comprises essentially a pair of opposed pistons 32 and 33 centrally interconnected by an axially extending piston rod assembly in'- cluding an inner rod 34, an outer valve tube 35, and a seal ring 36. Valve tube 35 is disposed aboutA rod 34 between the two pistons and has an external diameter corresponding to the internal diameter of bore 20 in the valve block to permit flow controlling cooperation with lthe block. The internal diameter of tube 35 is appreciably greater than the external diameter of rod 34 to vform with the rod an annular space through which pressure fluid is directed. O-ring 36 is disposed about rod 34 at its center to form a seal between the rod and the inner surface of the tube, dividing the annular clearance space between the tube and rod into a pair of fluid conducting passages 3'| and 38. At opposite sides of O-ring 36, tube 35 contains a pair of inlet ports 39 and 40, and a pair of outlet ports 4I andv42. adapted to cooperate with the inlet and outlet passages of the valve insert or block. At its ends, tube 35 presents openings or notches 43 and 44,

communicating respectively with upper and lower cylinder spaces 56 and 51 between the pistons and the transverse end surfaces 45 and 46 of the valve insert.

Each of the tool holder brackets 41 and 43 has an inner arm 49 clamped against the outer end surface 50 of its respective piston, and having an opening vpermittir-ig its reception about the corresponding end Yof rod 34. Thus, nuts 5I may be tightened on the ends of rod 34 to rigidly retain the tool holder brackets, the pistons, the rod and tube 35 in the illustrated relative positions for movement together as a unit.

Cylinder I6 has a longitudinally extending slot 52 at each end through which thel axially offset outwardly projecting portion 53 of the Ycorresponding tool holder bracket extends. Tool holder I2 is secured, at ,its ends, to transverse flanges 54 of the brackets, as by screws 55. `As previously brought out,Y the sanding board or other tool is removably secured to the tool holder byfscrews I4; y

lin using'the device, pressure fluid inlet- 22,- preferably'supplying compressed air, is secured to 'the intake side of valve I3, as shown in Figs. l

'and 4. Theoperator may then hold the device by handle I1 and, by'exer'ting linger pressure on bttnll, move plunger 21 of valve I3 inwardly to the open ci' fluid passing position. With the valve thus actuated, compressed air is permitted to pass through passage 2I and into whichever ofthe two intake ports '39 and 43 of valve tube '-35 happens to be in registry with the intake passage. For instance, if the piston and valve assembly is in the position illustrated `in Fig. 4, air passes from inlet passage 2I through valve port-40, axiallyalong annular passage 38, and radially outwardly throughl openings -4'4 into lower cylinder space 51 to move piston 33 downwardly.- At the same time, upper cylinder space 56' is in'communication with discharge passage 23 through end openings 43 of the valve tube, annular passage 31, and discharge port 4 I Thus, the'upper cylinder space is permittedto discharge during `the downward power stroke-of the lower piston. As the piston and valve assembly moves downwardly, valve tube 35 slides within block 'f8-"to reverse the valve connections for 'the up'- wa'rdipower stroke. 'That is, inlet .port 39 moves into registry with inlet passage 42| to supply air beneath' piston 5i),` and discharge port 42 moves to a point opposite discharge passage 24 to permit escape of the' air'from the lower cylinder space 51. Consequently the assembly reverses direction and moves upwardly under the Yinflul'ence of the air in space 51. This reciprocating 'said body and Amovable by 'luidlp'ressure in op- `posite directions, a r'od interconnecting said plstons, a tube of greater internal diameter'than-lthe external diameter of Ysaid rod and disposed about said rod between said pistons to 'form an'annular spacasaid tube and rod being movable with said pistons, an annular seal ring disposed aboutsaid -rod'and'within said tube at a central location lto formfauid seal therebetween dividing' said an -nula'r space longitudinally into fa pair vof annular fluid passages, pressure fluid inlet means, and

fluid discharge means, said tube .having Awall Vapertures in leohunuunicatio'n with said annular I'Il passages adapted to cooperate withsaid inlet means upon reciprocation to alternately admit pressure fluid through said passages to their respective pistons and adapted also to alternately discharge fluid through said passages and'said outlet means.

2. A reciprocating tool actuating device comprisinga cylinder body, a pair of lopposed reciprocable .pistons within said body, aj rod extending between and connected at opposite ends to said pistons, a tube formed separately from said rod and disposed thereabout between said pistons, said tube and rod being movable axially with the pistons, said tube being spaced from said rod to form fluid passage means therebetween', said body containing pressure fluid inlet and outlet ducts, and the wall of said tube having aperture means communicating with said iluid passage means between the rod and tube and cooperating with said inlet and outlet ducts in accordance with movement of the tube to control the delivery of pressure fluid to and from the pistons for eecting Areciprocation thereof.

3. A reciprocating tool actuating deviceas recited in claim 2, and including seal means received between said rod and tube at a location between the pistons and dividing said passage means into two separate passages each controlling the delivery of fluid to and its discharge from one `of said pistons.

.4. A `reciprocatingtool actuating device as re:- cited in claim 3, and including a tool holder reciprocable relative to the body and attached to said rod for movement therewith.

5. A reciprocating tool actuating device comprising a handle body containing a pair of alined cylindrical bores, a partition in the body between said bores, a pair of opposedreciprocable `pistons in said body bores respectively, a rod extending between and connected at its opposite ends to said pistons, a tube formed separately from'said rod and disposed thereabout between said, pistons, said tube and rod extending through an opening in said partition and being movable with the pistons, said tube being radially spaced from said rod to formrfiuid passage means therebetween, a resilient seal ring received between said rod and tube at a location between the pistons and dividing said passage means into two separate passages, said partition containing pressure fluid inlet and outlet ducts, the wall of said tube containing apertures opening into said passages and cooperating with said inlet and outlet ducts in accordance with movement of the tube to alternately admitliluid to and discharge it from said bores through said passages and thereby eifect reciprocation of the pistons, and a tool holder connected to and reciprocable with said pistons.

6. A reciprocating tool actuating device as recited in claim 5, in which said tool holder extends alongside and generally parallel to said bores, and including a pair of lugs projecting from said tool holder and attached directly to opposite ends of said rod.

7. A reciprocating tool actuating ydevice as recited in claim '6, .including a pair lofnuts threaded onto said opposite ends of said rod and tightening said lugs and pistons against said tube, fand in which said body 4bores are opposite end por'- tions 'of a single `cylindrical bore'. and said 'partition is .formed separately "from .the Vbody and receivedin a 'central portion of said single bore.

ALMA A. HU,y TCHIS.

(References on Vfollowing page) 6 REFERENCES CITED Number The following references are of record in the 1,506,219 le of this patent: UNITED STATES PATENTS 5 255:395 Number Name Date 2,350,779

80,550 Joy Aug. 4, 1868 539,240 Soley May 14, 1895 1,195,549 Baker Aug. 22, 1916 Number 1,238,062 Ekstrom Aug.21,191'1 10 54.934

Name Date Clark Aug. 26, 1924 Rolstad Jan. 19, 1932 Hampton Nov. 26, 1935 Spink Sept. 9, 1941 Lapkoff June 6, 1944 FOREIGN PATENTS Country Date Germany Jan. 12, 1891 

